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In the discussion following a recent question about whether the standard deviation can exceed the mean, one question was raised briefly but never fully answered. So I am asking it here.
Consider a set of $n$ nonnegative numbers
$x_i$ where $0 \leq x_i \leq c$ for $1 \leq i \leq n$. It is not
required that the $x_i$... |
I'm looking for a function to do that in R. I know how to write that function. Just don't want to reinvent something.
|
Following my question here, I will be most grateful for further assistance to clear my confusion.
The confusion is because I have read in many places that when you use ANCOVA in GLM (in SPSS), the effect of the covariate is controlled. I am unsure why it should be controlled in my case below (unless I am wrongly inter... |
Suppose we have $n$ covariates $x_1, \dots, x_n$ and a binary outcome variable $y$. Some of these covariates are categorical with multiple levels. Others are continuous. How would you choose the "best" model? In other words, how do you choose which covariates to include in the model?
Would you model $y$ with each of th... |
Problem: Consider two cars (taken to be point objects), named leader $L$ and follower $F$, both equipped with GPS devices that communicate with each other. The object of $F$ is to follow $L$ as closely as possible as the latter moves arbitrarily on the plane. Given that all GPS devices have a Circular Error Probable ... |
Disclaimer: I am a biologist, so please don't hesitate to correct me if I am making unwise assumptions.
I am looking at the distribution of a unique 6mer in a series of 2100mer (I have 415 independent 2100mer). More precisely, I am looking into how many times that 6mer is present in each 2100mer. As I deal with DNA seq... |
I have this income distribution data for various groups:
https://docs.google.com/spreadsheet/ccc?key=0Akwg3n_e05cCdEdtT0VZYU5keW5DVkNoNmpBWmdzeUE
As you can see, I have intervals/bins with varying widths. I also have an open-ended interval and the mean income in that open interval varies a lot between groups.
For pedag... |
I have many pairs like:
A B
10 20
15.3 19.5
23 13
45 32
etc etc,
I create those pairs calculating the standard deviation of many vectors (R vectors) and then group them by 2(A - B).
Now, I have to filter those pairs by their percentage difference.
I set a percentage like 30% then I filter all the pairs to get those ... |
Suppose I am modelling a binary outcome $y$ with $n$ covariates. If this model has the lowest AIC among all the other ones...would this be the one to use? Also in dealing with categorical variables, should you delete all levels or none? For example suppose a categorical variable $z$ has the following levels: $z_1, z_2$... |
I want to predict the outcome of a particular treatment (remitted or not) using demographic, plasma biomarker, genetic, and clinical data. IS a neural network model the best way of doing this? What advantages does this have over traditional logistic regression model building? How limited am I with only 120 cases and up... |
Can anyone show how the expected value and variance of the zero inflated Poisson, with probability mass function
$$
f(y) =
\begin{cases}
\pi+(1-\pi)e^{-\lambda}, & \text{if }y=0 \\
(1-\pi)\frac{\lambda^{y}e^{-\lambda}}{y!}, & \text{if }y=1,2....
\end{cases}
$$
where $\pi$ is the probability that the observation is zero... |
When I convert some data for a model (e.g., wealth, pollution) into per capita figures (e.g., wealth per inhabitant, tons of pollution per inhabitant) is this a transformation or re-expression of the data? Or is the term transformation or re-expression reserved for logarithmic or exponential transformations (including ... |
An example like the t-distribution with 2 degrees of freedom would not suffice as the second moment exists but equals inf.
|
I would like to prove the following statement:
If the $r$th moment of a random variable $X$ exists and is finite,
then all moments $1$ to $r-1$ exist and are finite.
Edit: I mean the raw moments $\mathbb E X^r$. By exists I mean exists and is finite.
|
As I am not very experienced in financial econometrics I need help in writing R code for MC simulation for VaR estimation. Namely, reading some books and reference manuals for R packages, I ended up with the following code:
-constructing hypothetical portfolio consisting of x1 and x2
p<-matrix(c(rnorm(1000,50,4),rnorm(... |
I dimly remember from my youth a quotation from a famous engineer or mathematician about the need for expressing values with a suitable number of digits, but can't remember it at the moment. It was something like
"Nothing shows ignorance faster than using more digits than is appropriate."
However my google-fu has f... |
I am trying to understand how Lars algorithm can be modified to generate Lasso. While I do understand LARS, I am not able to see the Lasso modification from the paper by Tibshirani et al. In particular I don't see why the sign condition in that the sign of the non-zero coordinate must agree with the sign of the current... |
Is there a way to calculate an estimate of the parameter $\kappa$ from data for the von Mises distribution?
It seems very easy to do in R, http://rgm2.lab.nig.ac.jp/RGM2/func.php?rd_id=CircStats:A1inv, but python doesn't have an A1inv function to calculate the ratio of the first and zeroth order Bessel functions of the... |
In testing gender difference on the relationship between variable A and B,
A is the covariate (or independent variable)
B is the dependent variable
Gender is the factor
As I understand it, if there is a significant interaction between the covariate and factor, then the analysis should be stopped as this violates an ... |
I have performed multiple linear regression analyses with different combinations of transformed and untransformed variables--both explanatory (independent) and response (dependent) variables. All transformations were $\log_{10}(X+1)$ which seem to fit/better fit assumptions of normality. Also, I have indicator (dummy) ... |
I'm using GARCH() function (tseries package) to fit garch model.
I tried it with random numbers: g <- garch(rnorm(750), order = c(1,1))
I know in this case the variance is constant BUT how to understand it reading the output of that function?
summary(g)
Call:
garch(x = rnorm(750), order = c(1, 1))
Model:
GARCH(1,1)
... |
I am interested in new generating samples to approximate some unknown distribution X, where each new sample is a real-valued vector.
The purpose it to be able to create a new (arbitrary large) stream of new samples from this approximate distribution that will be distributed in the same way, or as close as possible, to... |
I need to use Breusch-Pagan to check heteroscedasticity of my timeseries.
I found the explanation of the function, here: http://hosho.ees.hokudai.ac.jp/~kubo/Rdoc/library/lmtest/html/bptest.html
Looking at the example, I saw that the regressor is a simple serie with 1 -1 repeated values. Could someone explain me why ?
... |
I am comparing the Facebook posts of a TV news organization's Facebook Page to the contents of the TV news broadcast. (This is called "agenda setting" in communications research.) I have used a grounded theory approach to code hundreds of Facebook posts and segments of the TV show.
Here is the problem: There are about... |
I am surveying the use of statistical significance testing (SST) to validate the results of cluster analysis. I have found several papers around this topic, such as
"Statistical Significance of Clustering for High-Dimension, Low–Sample Size Data" by Liu, Yufeng et al. (2008)
"On some significance tests in cluster analy... |
Let us assume I have two data sets with n observations of data pairs of independent variable x and dependent variable y each. Let us further assume I want to generate a distribution of regression slopes for each data set by bootstrapping the observations (with replacement) N times and calculating the regression y = a +... |
I want to fit mixed model using lme4, nlme, baysian regression package or any available.
Mixed model in Asreml- R coding conventions
before going into specifics, we might want to have details on asreml-R conventions, for those who are unfamiliar with ASREML codes.
y = Xτ + Zu + e ........................(1) ;
the us... |
Data Augmentation Approach in Bayesian Modelling of Presence-only Data (Divino et al.) states that the data ware sampled from a normal distribution with mean 2.0 and a common variance (section 3). Does anyone know the value of a 'common variance'? Thanks.
|
I had a discussion with a friend of mine about what is the best course of action in the following Yahtzee scenario:
The first throw with 5 dice results in the following values:
1, 3, 4, 5, X, with X = 3, 4 or 5
Based on probability, what will be the best decision to make to end up with a large straight (1-2-3-4-5 or 2... |
I've created nice little nonlinear model relating survival probability to length in salmon. I fit it assuming binomial errors and minimizing the negative log likelihood. I've been asked to compare it to someone else's model, where they binned the data and fit a straight line to it. However, the lowest bin includes the ... |
Possible Duplicate:
How to interpret F- and p-value in ANOVA?
I found that I can use ANOVA also for ONE Model, doing something like:
> anova(lm(a~b))
Analysis of Variance Table
Response: a
Df Sum Sq Mean Sq F value Pr(>F)
b 1 0.002679 0.0026791 11.191 0.0009001 ***
Residuals 398 0.0... |
I'm familiar with supervised learning algorithms like regression and neural networks which look at a bunch of input points and learn a function which outputs a value (the value varying depending on whether the algo is a classifier, logistic regression, or standard regression)..but I am facing a problem now where each o... |
In answer to a previous question factor pooling in model selection was discussed.
If a factor or categorical variable is to be dropped in model selection, should all levels be dropped simultaneously? If so, why?
The motivation for dropping factors is to aid model interpretation. For example, I might be interested in ex... |
I am collecting a lot of data from neurons and will be analyzing each neuron separately. Is it valid to pick the best of several models based on the AICc for each neuron and then use the ANOVA p-values from the best model? Or should should I only run the AICc on preliminary data and then use the best model analyze ever... |
If the Hosmer-Lemeshow indicates a lack of fit but the AIC is the lowest among all the models....should you still use the model?
If I delete a variable, the Hosmer-Lemeshow statistic is not significant (which means there is no gross lack of fit). But the AIC increases.
Edit: I think in general, if the AIC's of differen... |
I am just wondering what does "to center two IVs" mean in the context of understanding an interaction. The IVs are A and gender and the DV is B.
Is it necessary for the main effects of a new interaction variable (A*Gender) to be a product (e.g. centered main effect of A * centered main effect of Gender) before the IVs ... |
I have a lot of $N$ devices, and I'd like to know if any of them are faulty. What sample size do I need in order to make sure with $100(1-\alpha)\%$ confidence that none are faulty?
|
It seems like the PACF graph is more informative than an ACF graph. What information does one get from an ACF graph that can not be gleaned from a PACF graph. (ACF = Auto-correlation function, and PACF = partial Autocorrelation).
|
In the card game Pitch using 1 deck with 52 cards and 4 people playing and six cards are dealt to each person and I have a partner and I have a King and wish to bid in the suit the King is in using the King as high what is the percentage my opponents have the Ace in the same suit as my King out of their 12 cards?
|
I am using Proc Arima to produce the Dickey-Fuller and the augmented Dickey-Fuller tests. According to documentation Proc Arima uses the Dickey-Fuller method that tests the following hypothesis:
H0: psi=0
H1: psi not 0
in the three regressions:
DYt=psi*Yt-1 + ut
DYt=intercept+psi*Yt-1 + ut
DYt=intercept + time trend... |
The case of regularization in a hilbert space is considered---an optimization problem with an error term and a Tikhonov-regularizer.
In the article "When is there a representer theorem" it is stated on page 2 (2508), and proofs are referred to, that the representer theorem holds when the regularizer is a nondecreasing ... |
I have some syntax for SPSS and it produces everything that I need perfectly, although for some reason it spits it out one tailed instead of two tailed. Is there any way of editing this syntax so that it uses a two tailed analyses?
REGRESSION
/DESCRIPTIVES MEAN STDDEV CORR SIG N
/MISSING LISTWISE
/STATISTICS COEFF OUTS... |
Feel free to direct me to where an answer can be found, but I've banged my head against this for a while and turn to you good people:
Scenario:
I have a bunch of non-exclusive two-dimensional data (location data) for several thousand unique observations of independent subjects:
Subject1, CategoryA, TypeB, two-dimension... |
Eg. such as those on this page http://store.steampowered.com/hwsurvey
Is there any ready-made software that can do this? Alternatively, any recommendations for other software that does something similar? I know this is not really a statistics question, but I feel very strongly that data should be presented in a neat an... |
I have written some code which uses AdaBoost to generate a set of weak classifiers. I'm finding, however, that when I use the resulting strong classifier to classify examples, it seems that almost every weak classifier classifies an example the same way. Either they all think it's negative, or they all think it's posit... |
I am somewhat new to data mining, and I am working on a classification model for movie rating prediction.
I have collected data sets from IMDB, and I am planning to use a decision trees and nearest neighbor approaches for my model. I would like to know which freely available data mining tool could provide the function... |
I am conducting a survey where I ask respondents to rate five factors on a scale from 1 to 100 on how much the factor affects an individual's perception of the value of a particular product.
How can I determine whether the valuation of the product is standard or not standard across respondents?
|
Possible Duplicate:
Hosmer-Lemeshow vs AIC: Logistic Regression
To assess the goodness of fit of a model... is the likelihood ratio test better than the H-L test in general?
|
Every week we have new customers sign up, and some of them submit support requests. I'd like to graph the change in the number of support tickets per customer over time. I'm doing this by bucketing customers into one-week cohorts, and then graphing each distribution as a Tufte box plot, as in this image. The graph I ha... |
I'm novice in time series analysis and completely lost through reading so..
I have an enormous dataset of discrete time series of aggregated events and I wish to fit each one of them into ARIMA models. Therefore I have to ensure that the time series are stationary, which I do through adf and kpss tests. However I wonde... |
I have a probability distribution and I'm trying to extract some information from it. Specifically, I'm trying to determine the mean, variance, and standard deviation.
Am I able to determine those from the distribution table, and if so, how should I approach the problem?
To further clarify on the nature of the data, he... |
Let's pretend I'm conducting a poll/survey. It's a simple yes/no poll (i.e. everyone only gives 1 of 2 answers). I have asked N people so far, and X of them have said "yes".
I would like to stop asking people (i.e. stop the poll) when I can be sure to some high level of statistical confidence (e.g. 95% sure) that I hav... |
I'd like to get some real practice with hypothesis testing that is above what's in textbooks (plug and chug, usually). I was hoping someone could suggest some good data sets and problems to work on. Problems that I could show others that I've worked on. Along those lines, I'd very much appreciate any top notch referenc... |
I am studying the Dickey Fuller test. The book of reference is Introductory Econometrics for Finance by C. Brooks. I firstly consider the zero mean Dickey Fuller test that uses the "random walk" type of regression:
$\Delta Y_t = \delta Y_{t-1} + u_t$
The null hypothesis is that $\delta$ is zero and the alternative is t... |
Firstly, please forgive my lack of statistics knowledge, but I am hoping someone can clear up my misunderstandings.
I am taking a sample of a physical quantity, (for example: temperature). To take this sample I average the measurements over a time duration (for example: 1 sec). This gives me a sample mean and a sample ... |
I have a traditional logit model with a dichotomous dependent variable and several independent variables. One of the IVs is categorical and in my R code, I treat it as a factor.
In the past, I've presented marginal effects by creating a simulated dataset in which I hold all variables at their mean or median and then i... |
I am new to Machine Learning. At the moment I am using a Naive Bayes (NB) classifier to classify small texts in 3 classes as positive, negative or neutral, using NLTK and python.
After conducting some tests, with a dataset composed of 300,000 instances (16,924 positives 7,477 negatives and 275,599 neutrals) I found tha... |
I am analysing hourly demand data for electricity. To make my forecasts more accurate, how should I treat the national holidays in the data?
In particular, how should I treat them in R?
|
In a text mining application, one simple approach is to use the $tf-idf$ heuristic to create vectors as compact sparse representations of the documents. This is fine for the batch setting, where the whole corpus is known a-priori, as the $idf$ requires the whole corpus
$$
\mathrm{idf}(t) = \log \frac{|D|}{|\{d: t \in ... |
When we consider Queueing theory scenarios where individuals arrive to a serving node and queue up, usually a Poisson process is used to model the arrival times. These scenarios come up in network routing problems. I'd appreciate an intuitive explanation as to why a Poisson process is best suited to model the arrivals.... |
I have some doubts about cross validation and scoring a new set of observations.
Let's say I want to predict $y=b_0 + b_1x_1$ and have built a 10-fold cross-validation data set, run a regression model and calculated RMSE, MAE, CV and R-squared and let's say I am happy with results.
Now I have 10 regression models (one ... |
I wish to use raw data about clinical trials for the end year examination of my master students. These data could deal with any kind of molecule as long as the trials were complete (Phase 1 to 4).
Do you have an idea where to find such a free dataset on the web ?
|
I’m somewhat lost as to how to approach a problem I have and was hoping someone can suggest the most appropriate method.
The problem:
I have a data set consisting of concentration values for 8 molecules. These are measured on approx. 230 samples from approx. 70 patients. For many patients there are multiple samples ta... |
I am currently implementing a application that needs to obtain the inverse of the F (Fisher-Snedecor) cumulative distribution.
I already have a library that contains the F distribution and I can easily obtain the cumulative distribution based on a confidence interval and degrees of freedom.
How can I easly adapt this l... |
Say I have some historical data e.g., past stock prices, airline ticket price fluctuations, past financial data of the company...
Now someone (or some formula) comes along and says "let's take/use the log of the distribution" and here's where I go WHY?
Questions:
WHY should one take the log of the distribution in the ... |
I am looking for a list of stochastic algorithms to approximate likelihoods.
|
I have come across these two terms which are used interchangeably in many contexts.
Basically, a moderator (M) is a factor that impacts on the relationship between X and Y. Moderation analysis is usually done using a regression model. For example, gender (M) can affect the relationship between "product research" (X) an... |
I have tested 100 bacterial isolates for resistance to 6 antibiotics (tetracycline, erythromycin, kanamycin, streptomycin, gentamicin, chloramphenicol). The result for any antibiotic could be either sensitive (1) or resistant (0).
How can I determine if there is any significant association between resistance to variou... |
Can you just eyeball the Hosmer-Lemeshow test (e.g. just look at observed and expected values in each group and see if they agree more or less)? Even if the Hosmer-Lemeshow statistic is significant...can I still say the model fits the data well for my purposes just by observing the observed and expected values in each ... |
Is there an issue with the output of the Huynh-Feldt correction when running an ANOVA for both between and within factors (mixed design) in R? My issue is that when I run a 'within-subject (only)' ANOVA using either the 'Anova' or 'ezANOVA' functions, the output for the Huynh-Feldt correction is the exact same I get wh... |
I came across the word subjective interestingness measures in my book, where author says that:
Subjective interestingness measures are based on user belief in the
data. These measures find patterns interesting if they are unexpected
(contradicting user's belief) or offer strategic information on which
user can a... |
In text classification, I have a training set with about 800 samples, and a test set with about 150 samples. The test set has never been used, and waiting to be used until the end.
I am using the whole 800 sample training set, with 10 fold cross validate while tuning and tweaking classifiers and features. This means I ... |
Does any know how to draw a graph like this:
Which programs can do that? I'm a developer so I've no problem on formatting a complex files so that a software can handle it.
|
I have two graphical models that have significant overlap in the random variables they are modeling. Is it possible to use samples from one graphical model to avoid sampling as much from the other graphical model?
As an example can I use samples from an empirical bayes approach in estimating the distribution in a full ... |
I am looking through Time Series Analysis: With Applications in R (my first exposure to time series) and refreshing summations.
I.
When given the following rule:
COV[$\sum_{i=1}^{m} c_{i}Y_{t_{i}},\sum_{j=1}^{n} d_{j}Y_{s_{j}}$] = $\sum_{i=1}{m}\sum_{j=1}^{n}c_{i}d_{j}Cov(Y_{t_{i}},Y_{s_{j}})$
and then encounter COV{$\... |
Is there a statistical reason why item analysis/response theory isn't more widely applied? For instance, if a teacher gives a 25 question multiple choice test and finds that 10 questions were answered correctly by everyone, 10 questions were answered by a really low fraction (say 10%) and the remaining 5 were answered ... |
I'm testing for mutations in DNA and I'm using the Benjamini-Hochberg method to modify the threshold I'm testing my p-values against. The method is basically to rank the p-values and compare them to a new threshold defined by
$q(k) = k/n*\alpha$,
where $\alpha$ is your original threshold, commonly 0.05, $k$ is the rank... |
Following the question here, I have come across different (textbook) recommendations.
Some authors suggest that the effect of the moderating variable is best understood in a graphic form.
Others suggest that after graphing the effect, further significance testing should be undertaken to ascertain if the pattern (in the... |
Wikipedia tells us that the score plays an important role in the Cramér–Rao inequality. It also phrases out the definition:
$$V = \frac{\partial}{\partial \theta} \log{L(\theta; X)}$$
However, I cannot find an intuitive explanation of what this quantity expresses. Obviously, it somehow measures how a small change of $\... |
A commonly used goodness of fit statistic for logistic regression is the deviance. This is also known as the likelihood ratio chi-square statistic. It is defined as:
$$D=\sum_{i=1}^{N}d_i^2$$
$$d_i^2=2y_i\log\left(\frac{y_i}{n_ip_i}\right)+2(n_i-y_i)\log\left(\frac{n_i-y_i}{n_i-n_ip_i}\right)$$
Where $N$ is the numbe... |
I've been gathering data for the usage of a web app.
For each day at the same hour and over several months I have:
(A) total number of members
number of online members and its % to (A)
number of members who connected during the day and its % to (A)
number of new members
number of forum members
number of new foru... |
Recently I have opened a question here to understand the output of a GARCH model.
My goal is to understand if the series I'm checking is heteroscedastic or not.
I'm using the garch() function from the tseries package.
First I built a linear regression like this:
mod <- lm(a ~ b)
Then I need to check if the residuals o... |
I'm a SQL/C++ developer who recently has been asked to generate a report from our database to predict some future performance based on historical data; the problem is that I don't have much experience of this sort of data modelling.
I initially thought I could take an average of each month's results and use that but af... |
In OLS regression, I find the semipartial correlation (a.k.a. part correlation) to be a very useful indicator. When squared, it shows each predictor's unique contribution to explained variance in the outcome. If one tries several models, entering predictors in various orders, the semipartial correlation will always t... |
Is likelihood ratio test ($F$-test) of significance of difference of two linear models the same as chi-square test of difference of $-2\log L$?
SAS PROC GLM produces $F$-statistics and PROC MIXED $-2\log L$.
|
Wikipedia has a Fisher transform of the Spearman rank correlation to an approximate z-score. Perhaps that z-score is the difference from null hypothesis (rank correlation 0)?
This page has the following example:
4, 10, 3, 1, 9, 2, 6, 7, 8, 5
5, 8, 6, 2, 10, 3, 9, 4, 7, 1
rank correlation 0.684848
"95% CI for rho (Fish... |
I'm trying to understand the statistical analysis I saw in a clinical study. They measured performance of 3 groups of subjects with a series of performance measures (A, B, C, ..., N). The objective was to find out if there was a difference between the performance of the 3 groups, and if yes, then in which ways they dif... |
What's the similarities and differences between these 3 methods:
Bagging,
Boosting,
Stacking?
Which is the best one? And why?
Can you give me an example for each?
|
I have a two years of daily data. The data for one month is missing as it was not recorded due to some problems at the company. How should I treat the data with no values for a month.
|
Possible Duplicate:
Practical thoughts on explanatory vs. predictive modeling
This question has been bugging me for some time, and I was going to write a blog post about it. However, I think it is better left for discussion in this forum.
Back in April, I attended a talk at the UMD Math Department Statistics group ... |
In text mining, if we've computed n-gram counts, for say $n=1\ldots4$, is there a principled way to combine them, other than just concatenating the $tf-idf$ matrices for each one? (equivalent to an unweighted sum of kernels if we were to construct kernel matrices for each one). For example, google's n-gram viewer:
http... |
I am studying the stationarity and invertibility conditions of AR processes.
Concerning the stationarity condition of the simplest form of an AR(1) process (without constant, drift). Let us say that we convert such an AR process to an infinite MA process. If we take the expected value of the new form of the process (th... |
I am looking for large (>1000) text corpus to download. Preferably with world news or some kind of reports. I have only found one with patents. Any suggestions?
|
I came across the following link. https://stackoverflow.com/questions/2764116/tag-generation-from-a-small-text-content-such-as-tweets
The question is about how do we assign tag to tweets automatically, the answer suggest using pointwise mutual information, however, my question is if how can we achieve it?
If we have 10... |
I have an ordinal variable related to an outcome that is comprised of many levels and I´d like to collapse the number of ordinal values as much as possible.
> require(ipred)
> require(party)
> data(GBSG2)
> head(GBSG2)
horTh age menostat tsize tgrade pnodes progrec estrec time cens
1 no 70 Post 21 II ... |
This is the question arised from my previous question. Basically, I am trying to build a prediction model for movie's rating. So I have to deal with numeric attribute such as actor_id, director_id, budget, etc., in my data set. So my question is how I should deal with those attributes for my classification.
|
I am not a statistician, so please excuse my lack of statistics knowledge/terminology.
I have bunch of network nodes that I want to run cluster analysis on and identify clusters. So as far as I understand, I can follow the following steps to run a hierarchical agglomerative analysis (HAC):
Identify variables
Define a... |
I know correlation does not imply causation. I have read it nth time. (i.e. weight does not cause height etc. etc.)
However, to find the effect of a moderator variable on X-Y relationship, a regression model is used such as the GLM in SPSS to test for interaction or multiple regression. See here.
My Question: If the X-... |
I am using logistic regression to predict y given x1 and x2:
z = B0 + B1 * x1 + B2 * x2
y = e^z / (e^z + 1)
How is logistic regression supposed to handle cases in which my variables have very different scales? Do people ever build logistic regression models with higher-order coefficients for variables? I'm imagining s... |
Please first have a look at the following little problem:
There are two indistinguishable light bulbs A and B. A flashes red
light with prob .8 and blue with prob .2; B red with .2 and blue .8.
Now with .5 prob you are presented with either A or B. You're supposed
to observe its flash color to make a best guess ... |
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